COMMUNIST PARTIES  
In the years following World War I and the Russian Revolution, Communism become a movement, distinct from the mainstream socialist movement. Its distinctive features were a commitment to Leninism and allegiance to the Union of Soviet Socialist Republics (USSR). World War I caused the dissolution of the Second International (created in 1889). The majority of socialists, including the powerful German and French parties, decided to support their own national governments. A minority, including the Russian Social Democratic Labour party (of which the Bolsheviks led by Vladimir Illich Lenin were still a part) remained loyal to the anti-war positions repeatedly upheld by the Second International in the years leading up to 1914. In 1917, months before the Russian Revolution, Lenin re-examined Marx's distinction between the lower and higher phase of communism in his Gosudarstvo i Revolyutsiya (The State and Revolution), called the lower phase "socialism" and reserved the term "communism" for the higher phase in which there would be neither a state nor social classes. The state would still exist in the socialist phase. It would take the form of a "dictatorship of the proletariat"—a term rarely found in the writings of Marx and Engels. The purpose of this was to prepare the way for communism by combating "bourgeois" ideas and habits swiftly and severely. This dictatorship, explained Lenin, is "not our ultimate goal...but a necessary step for the purpose of thoroughly purging society of all the hideousness and foulness of capitalist exploitation, and for further progress".

Following the successful seizure of power by the Bolsheviks in Russia in October 1917, Lenin's supporters in the rest of Europe agreed that it was not necessary to await the full development of capitalism before starting the construction of a socialist society leading to communism. They assumed that the conditions were ripe for a communist revolution which would spread throughout the world. This revolution would abolish capitalism and set up a socialist state, not a communist one, for, strictly speaking, a "communist state" is a contradiction in terms since communism is a classless society which administers itself without coercion and hence without a state. This is why all states established by Communists called themselves either "socialist", as in the Union of Socialist Soviet Republics, or "People's Republics" (for example, China) or "Democratic Republics" (for example, East Germany). To implement this vision a new organization was created, the Communist International (1919) or Comintern whose headquarters would be in Moscow, the new capital of the USSR. Sympathizers of the Bolsheviks in the various socialist parties were urged to form new parties to be called "Communist". These would be organized on rigidly militarist and centralized lines. An iron discipline ("democratic centralism") would prevail. Party cadres would be dedicated professional revolutionaries. Their task would be to demarcate themselves clearly from all other socialists who were deemed to be incurably reformist, and to prepare for an insurrection. By 1921 the working-class unrest which had rocked Europe after the war had ebbed while the Bolsheviks had consolidated their power in Russia. The probability of a worldwide conflagration had decreased considerably. By then, however, virtually all the socialist parties had split and Communist parties had been established. They quickly became heavily dependent on the USSR. Their relationship with the socialist and social-democratic parties from which they had separated was determined by the vicissitudes of the power struggle within the USSR and the changing requirements of Soviet diplomacy. Bitter denunciation of socialists as "social-fascist" in 1928-1934 was followed by invitations to form a common front (the Popular Front) against fascism. Throughout the inter-war period, no Communist parties succeeded in ousting any of the socialist parties from their dominant position in the labour movement.